Radio Frequency Response of the Strongly Interacting Fermi Gases at Finite Temperatures

TL;DR

This study investigates the radio frequency response of strongly interacting Fermi gases at finite temperatures, using Monte Carlo simulations to explore pairing phenomena and effective mass effects relevant to ultracold atomic systems.

Contribution

The paper introduces a Monte Carlo approach to analyze RF spectra of unitary Fermi gases at finite temperatures, revealing insights into pairing gaps and effective mass modifications.

Findings

Qualitative agreement with pairing gap-pseudogap transition

Effective mass estimated at approximately 1.43 times the bare mass

Implications for adiabatic magnetic field sweep processes

Abstract

The radio frequency spectrum of the fermions in the unitary limit at finite temperatures is characterized by the sum rule relations. We consider a simple picture where the atoms are removed by radio frequency excitations from the strongly interacting states into a state of negligible interaction. We calculate the moments of the response function in the range of temperature $0.08 \epsilon_F < T < 0.8 \epsilon_F$ using auxiliary field Monte Carlo technique (AFMC) in which continuum auxiliary fields with a density dependent shift are used. We estimate the effects of superfluid pairing from the clock shift. We find a qualitative agreement with the pairing gap - pseudogap transition behavior. We also find within the quasiparticle picture that in order for the gap to come into quantitative agreement with the previously known value at T=0, the effective mass has to be $m^* \sim 1.43 m$. Finally, we discuss implications for the adiabatic sweep of the resonant magnetic field.